Energy recovery of lignocellulosic waste material in the form of liquid fractions can yield alcohol-based fuels such as bioethanol or biobutanol. This study examined biobutanol derived from lignocellulosic material that was then used as an additive for diesel engines. Biobutanol was used in fuel mixtures with fatty acid methyl ester (FAME) obtained by esterification of animal fat (also a waste material) in the amounts of 10%, 30%, and 50% butanol. 100% diesel and 100% FAME were used as reference fuels. The evaluation concerned the fuel's effect on the external speed characteristics, harmful exhaust emissions, and fuel consumption while using the Non-Road Steady Cycle test. When the percentage of butanol was increased, the torque and the power decreased and the brake specific fuel consumption increased. The main advantage of using biobutanol in fuel was its positive effect on reducing the fuel's viscosity.

The global concentration of greenhouse gasses in the atmosphere is increasing as well as the emissions of harmful pollutants. Utilization of liquid biofuels in combustion engines helps to reduce these negative effects. For diesel engines, the most common alternative fuels are based on vegetable oils. Blending neat vegetable oils with diesel and/or alcohol fuels is a simple way to make them suitable for diesel engines. In this study, coconut oil was used in ternary fuel blends with diesel and butanol. Coconut oil is a potentially usable source of renewable energy, especially in the Pacific, where it is a local product. Diesel fuel-coconut oil-butanol fuel blends were used in concentrations of 70%/20%/10% and 60%/20%/20%, and 100% diesel fuel was used as a reference. The effect of the fuel blends on the production of harmful emissions, engine smoke, performance parameters, fuel consumption and solid particles production was monitored during the measurement. The engine was kept at a constant speed during the measurement and the load was selected at 50%, 75% and 100%. From the results, it can be stated that in comparison with diesel fuel, specific fuel consumption increased with a positive effect on the reduction of engine smoke.

The diesel fuel consumption affects the costs of transport in a significant manner. All measures leading to its minimization are therefore important. The proper formation of the transport combinations is one of such measures, i.e. selecting the power traction means to the trailer whose engine will run in the optimum working regime most of the time in the course of the transport operation, when its specified fuel consumption achieves low values. Vitlox and Michot (2005) dealt with the effect of the rated engine power utilization on the specific fuel consumption when cultivating soil with rotary harrows. They found that, when using rotary harrows with the 3 m engagement and 4 km/h working speed, the input power was 24 kW and the specific fuel consumption was 330 g/kWh. If the working speed increased to 7 km/h and the engagement to 4.5 m while all other parameters remained unchanged, the input power was 65 kW, however, the fuel consumption decreased to 242.5 g/kWh.Bauer et al. (2006) give an example of an engine running in two regimes at the same 150 kW power output, but at different speeds. In the first regime, the engine runs at 2000 min -1 and the fuel consumption is 230 g/kWh, in the second regime, it runs at 1770 min -1 and the fuel consumption is 210 g/kWh. The difference in the hourly consumption between both regimes is therefore 3.7 l/h. With the diesel fuel price of CZK 27 per litre, the difference is 100 CZK/h in fuel costs. MATERIAL AND METHODSThe goal of this work was the determination of how the change of the tractor engine rated power in a transport combination affects the diesel fuel consumption related to the unit of the transport output (l/tkm) and the transport performance (t/h) in the conditions of a mountainous region.First, a theoretical analysis of the diesel fuel consumption was carried out according to the available literature references when using different engine power in the tractor-trailer working combinations.The measurement was carried out in the territory of the Šumava Nicov farm which is situated in the sloping Abstract: The authors of this paper determined in a field measurement how the change of the tractor engine power in a tractor-trailer combination affects the diesel fuel consumption related to the unit of transport output (l/tkm) and the transport performance (t/h) in the conditions of a mountainous region. Transport combinations (tractor -trailer) were compared that were formed by a tipping trailer connected to three tractors with different engine powers when passing allong a route with the gradient of 0°-5.5°. It is obvious from the results of these measurements that the diesel fuel consumption differed by up to 27% in individual combinations. The lowest specific consumption on the measured route was found in the combination with the tractor with the engine rated power of 50 kW (0.037 to 0.077 l/tkm), the highest consumption with the tractor with the rated engine power of 114 kW (0.056 to 0.093 l/tkm). The lowest transport performance on the measured route was found in the...

Based on many regulations the biofuels are widely used in combustion engines. The operational parameters, such as performance parameters or emission production, are often monitored. The essence of changes to these operational parameters is related to the effect of biofuels on the course of cylinder pressure inside the combustion chamber. The contribution deals with the effect of biobutanol-sunflower oil-diesel fuel blends on the performance parameters, the behaviour of the cylinder pressure of the compression ignition engine during combustion, and exhaust gas temperature. Biobutanol-sunflower oil-diesel fuel blends in ratios of 10–20–70% and 20–20–60% were used as test fuels, with diesel fuel used as a reference. Turbocharged four-cylinder inline CI engine Zetor 1204 installed in the tractor Zetor Forterra 8642 was used for measurement. Based on the results, it can be stated that with higher amount of butanol in the fuel mixture, the maximum value of cylinder pressure decreases, especially at a high engine load.

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